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NASA NTRS1992

NASA's ultraviolet astrophysics branch - The next decade

We review some of the mission concepts currently being considered by NASA's Astrophysics Division to carry out future observations in the 100-3000 Angstrom region. Examples of possible future missions include UV and visible interferometric experiments, a next generation Space Telescope and lunar-based UV instrumentation. In order to match the science objectives of these future missions with new observational techniques, critical technology needs in the ultraviolet regime have been identified. Here we describe how NASA's Astrophysics Division Advanced Programs Branch is attempting to formulate an integrated technology plan called the 'Astrotech 21' program in order to provide the technology base for these astrophysics missions of the 21st century.

Welsh, Barry Y.↗
NASA NTRS1993

Solar-Stellar Irradiance Comparison Experiment 1. II - Instrument calibrations

The science objective for the Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) is to accurately measure the full disk solar spectral irradiance in the ultraviolet (UV) spectral region over a long time period. The SOLSTICE design was driven by the requirement for long-term, precise solar photometry conducted from space. The SOLSTICE 1 is on the Upper Atmosphere Research Satellite (UARS), launched in September 1991 with the possibility for a 10-year operational mission. The in-flight calibration for SOLSTICE to meet its primary objective is the routine measurements of the UV radiation from a set of early-type stars, using the identical optical elements employed for the solar observations. The extensive preflight calibrations of the instrument have yielded a precise characterization of the three SOLSTICE channels. Details of the preflight and in-flight SOLSTICE calibrations are discussed in this paper.

Woods, Thomas N.↗
NASA NTRS1992

Advanced optical instruments technology

The science objectives for proposed NASA missions for the next decades push the state of the art in sensitivity and spatial resolution over a wide range of wavelengths, including the x-ray to the submillimeter. While some of the proposed missions are larger and more sensitive versions of familiar concepts, such as the next generation space telescope, others use concepts, common on the Earth, but new to space, such as optical interferometry, in order to provide spatial resolutions impossible with other concepts. However, despite their architecture, the performance of all of the proposed missions depends critically on the back-end instruments that process the collected energy to produce scientifically interesting outputs. The Advanced Optical Instruments Technology panel was chartered with defining technology development plans that would best improve optical instrument performance for future astrophysics missions. At this workshop the optical instrument was defined as the set of optical components that reimage the light from the telescope onto the detectors to provide information about the spatial, spectral, and polarization properties of the light. This definition was used to distinguish the optical instrument technology issues from those associated with the telescope, which were covered by a separate panel. The panel identified several areas for optical component technology development: diffraction gratings; tunable filters; interferometric beam combiners; optical materials; and fiber optics. The panel also determined that stray light suppression instruments, such as coronagraphs and nulling interferometers, were in need of general development to support future astrophysics needs.

Shao, Mike↗
NASA NTRS1992

NASA's Ultraviolet Astrophysics Branch: Present and future detector program

The various concepts in ultraviolet detector technology currently being funded by NASA's Astrophysics Division to carry out observations in the 100 to 3000 A region are reviewed. In order to match the science objectives of future space missions with new observational techniques, critical detector technology needs in the ultraviolet regime have been identified. The attempt by NASA's Astrophysics Division Advanced Programs Branch to formulate an integrated detector technology plan as part of the ongoing 'Astrotech 21' program in order to provide the technology base for these astrophysics missions of the 21st century is described.

Welsh, Barry Y.↗
NASA NTRS1993

Mars exobiology landing sites for future exploration

The selection of landing sites for Exobiology is an important issue for planning for future Mars missions. Results of a recent site selection study which focused on potential landing sites described in the Mars Landing Site Catalog are presented. In addition, basic Exobiology science objectives in Mars exploration are reviewed, and the procedures used in site evaluation and prioritization are outlined.

Landheim, Ragnhild↗
NASA NTRS1993

Balloon exploration of the northern plains of Mars near and north of the Viking 2 landing site

The next stage of exploratory surveying of the northern plains of Mars after the Mars Observer mission may best be done by Mars Balloon Exploration Vehicles (MBEV's) deployed in the atmosphere above the northern plains near and north of the Viking 2 lander (VL-2) landing site. This region of Mars is favorable for exploration by MBEV's for the following reasons: (1) the low surface elevation (approximately 2km, lower than the standard (zero) elevation of the Martian surface) provides atmospheric pressure sufficient to allow a MBEV to successfully operate and explore this region at the present stage of MBEV design and development; and (2) the relatively smooth nature of the northern plains terrain (few mountains, ridges, valleys, and craters) indicated so far by Mariner 9 and Viking Orbiter data seems adequate for operation of a MBEV when its SNAKE extension is in contact with the surface of one of these plains. The science objectives are presented.

West, Frederick R.↗
NASA NTRS1993

Design of a surface deformation measuring instrument for the Surface Tension Driven Convection Experiment (STDCE-2)

This final technical report covers the work accomplished (under NAG3-1300) from 1 October 1991 to 1 October 1993. The grant is a direct result of Dr. H. Philip Stahl's (of Rose-Hulman Institute of Technology) participation in the NASA/ASEE Summer Faculty Fellowship Program at NASA Lewis Research Center sponsored by Case Western Reserve University and the Ohio Aerospace Institute. The Surface Tension Driven Convection Experiment (STDCE) is a fundamental fluid physics experiment designed to provide quantitative data on the thermocapillary flow of fluid under the influence of an increased localized surface temperature. STDCE flew on the Space Shuttle Columbia in the First United States Microgravity Laboratory (USML-1) in June 1992. The second flight of this experiment (STDCE-2) is scheduled for 1995. The specific science objectives of STDCE-2 are to determine the extent and nature of thermocapillary flows, the effect of heating mode and level, the effect of the liquid free-surface shape, and the onset conditions for and nature of oscillatory flows. In order to satisfy one of these objectives, an instrument for measuring the shape of an air/oil free surface must be developed.

Stahl, H. Philip↗
NASA NTRS1993

The Far Ultraviolet (FUV) auroral imager for the Inner Magnetospheric Imager (IMI) mission: Options

The change from an intermediate mission (cost ceiling of $300 million) to a solar-terrestrial probe class mission (cost ceiling of $150 million) will require some major changes in the configuration of the IMI mission. One option being considered is to move to a small spin-stabilized spacecraft (with no despun platform) which could be launched with a smaller Taurus or Conestoga class booster. Such a change in spacecraft type would not present any fundamental problems (other than restrictions on mass and power) for the He plus 304 A plasmasphere imager, the high and low energy neutral atom imagers, and the geocoronal imager, but would present a challenge for the FUV auroral imager since the original plan called for this instrument to operate from a despun platform. Since the FUV instrument is part of the core payload it cannot be dropped from the instrument complement without jeopardizing the science goals of the mission. A way must be found to keep this instrument and to allow it to accomplish most, if not all, of its science objectives. One of the subjects discussed are options for building an FUV instrument for a spinning spacecraft. Since a number of spinning spacecraft have carried auroral imagers, a range of techniques exists. In addition, the option of flying the FUV imager on a separate micro-satellite launched with the main IMI spacecraft or with a separate pegasus launch, was considered and is discussed.

Wilson, Gordon R.↗
NASA NTRS1993

A broad-band microseismometer for planetary operations

There has recently been renewed interest in the development of instrumentation for making measurements on the surface of Mars. This is due to the Mars Environmental Survey (MESUR) Mission, for which approximately 16 small, long-lived (2-10 years), relatively inexpensive surface stations will be deployed in a planet-wide network. This will allow the investigation of processes (such as seismology and meteorology) which require the simultaneous measurement of phenomena at many widely spaced locations on the surface over a considerable length of time. Due to the large number of vehicles involved, the mass, power, and cost of the payload will be severely constrained. A seismometer has been identified as one of the highest priority instruments in the MESUR straw-man payload. The requirements for an effective seismic experiment on Mars place a number of constraints on any viable sensor design. First, a large number of sensors must be deployed in a long-lived global network in order to be able to locate many events reliably, provide good spatial sampling of the interior, and increase the probability of seismic detection in the event of localized seismicity and/or high attenuation. From a practical standpoint, this means that individual surface stations will necessarily be constrained in terms of cost, mass, and power. Landing and thermal control systems will probably be simple, in order to minimize cost, resulting in large impact accelerations and wide daily and seasonal thermal swings. The level of seismic noise will determine the maximum usable sensitivity for seismometer. Unfortunately, the ambient seismic noise level for Mars is not well known. However lunar seismic noise levels are several orders of magnitude below that of the Earth. Sensitivities on the order of 10(exp -11)g over a bandwidth of .04 to 20 Hz are thought to be necessary to fulfill the science objectives for a seimometer placed on the Martian surface. Silicon micromachined sensor technology offers techniques for the fabrication of monolithic, robust, compact, lower power and mass accelerometers. Conventional micro-machined accelerometers have been developed and are commercially available for high frequency and large acceleration measurements. The new seismometer we are developing incorporates certain principles of conventional silicon micromachined accelerometer technology. However, currently available silicon micromachined sensors offer inadequate sensitivity and bandwidth for the Mars seismometer application. Our implementation of an advanced silicon micromachined seismometer is based on principles recently developed at JPL for high-sensitivity position sensor technology.

Banerdt, W. B.↗
NASA NTRS1994

TRMM-related research: Tropical rainfall and energy analysis experiment

The overall science objective of the participation in TRMM is the determination of daily rainfall and latent heating in the tropical atmosphere using TRMM and complementary spacecraft observations. The major focus these first three years has been to extend, in space and time, the TRMM satellite observations of rainfall. Observations from TRMM active and passive microwave radiometers will provide the fundamental observations for understanding the hydrological cycle of the tropics. Due to the orbit of the TRMM satellite and the extreme variability of convective rain systems, the TRMM observations provide rainfall estimates representative of a one month period. Monthly mean rainfall rates provide valuable information; however, this time scale limitation neglects the great value of the data towards a better understanding of the physics of tropical convection. Many tropical periodicities will not be characterized by these monthly averages, e.g. diurnal cycles, the 4-6 day easterly waves, and the 30 to 60 day cycle. In the spatial domain, due to its orbit, the TRMM satellite will over-fly many convective systems only once. Indeed, some precipitating systems will not be sampled at all. Observations from geostationary satellites can be used to extend the TRMM observations to smaller time and space scales. Although geostationary satellites cannot probe the interiors of precipitating systems, they do observe their life cycles. To acquire information on cloud water content and rain rate, it is proposed to combine geostationary and other satellite observations with the TRMM satellite measurements.

Suomi, Verner E.↗
NASA NTRS1994

Remote geochemical experiment package for Discovery class missions

Remote sensing x-ray and gamma-ray spectrometers can be used to infer elemental composition on atmosphereless bodies, such as asteroids, the moon, and Mercury. The composition of the planetary body and variations in its surface chemistry are of fundamental importance in understanding the formation and dynamics of that body. Thus, for Discovery class missions, x-ray fluorescence (XRF), gamma-ray spectrometer (GRS), or a combined Geochemical Experiment Package (GEP) have been proposed. These instruments can meet the mission science objectives, while still meeting the weight, power, and cost constraints. These missions include the Near Earth Asteroid Rendezvous, the Main-belt Asteroid Rendezvous, and others such as HERMES (Mercury Orbiter). This paper presents the results of calculations done to assess the sensitivity of a combined instrument to obtain elemental compositions of planetary bodies with an uncertainty small enough to be scientifically useful.

Clark, Pamela E.↗
NASA NTRS1993

Training for life science experiments in space at the NASA Ames Research Center

As this country prepares for exploration to other planets, the need to understand the affects of long duration exposure to microgravity is evident. The National Aeronautics and Space Administration (NASA) Ames Research Center's Space Life Sciences Payloads Office is responsible for a number of non-human life sciences payloads on NASA's Space Shuttle's Spacelab. Included in this responsibility is the training of those individuals who will be conducting the experiments during flight, the astronauts. Preparing a crew to conduct such experiments requires training protocols that build on simple tasks. Once a defined degree of performance proficiency is met for each task, these tasks are combined to increase the complexity of the activities. As tasks are combined into in-flight operations, they are subjected to time constraints and the crew enhances their skills through repetition. The science objectives must be completely understood by the crew and are critical to the overall training program. Completion of the in-flight activities is proof of success. Because the crew is exposed to the background of early research and plans for post-flight analyses, they have a vested interest in the flight activities. The salient features of this training approach is that it allows for flexibility in implementation, consideration of individual differences, and a greater ability to retain experiment information. This training approach offers another effective alternative training tool to existing methodologies.

Rodrigues, Annette T.↗
NASA NTRS1993

The rhesus measurement system: A new instrument for space research

The Rhesus Research Facility (RRF) is a research environment designed to study the effects of microgravity using rhesus primates as human surrogates. This experimental model allows investigators to study numerous aspects of microgravity exposure without compromising crew member activities. Currently, the RRF is slated for two missions to collect its data, the first mission is SLS-3, due to fly in late 1995. The RRF is a joint effort between the United States and France. The science and hardware portions of the project are being shared between the National Aeronautics and Space Administration (NASA) and France's Centre National D'Etudes Spatiales (CNES). The RRF is composed of many different subsystems in order to acquire data, provide life support, environmental enrichment, computer facilities and measurement capabilities for two rhesus primates aboard a nominal sixteen day mission. One of these subsystems is the Rhesus Measurement System (RMS). The RMS is designed to obtain in-flight physiological measurements from sensors interfaced with the subject. The RMS will acquire, preprocess, and transfer the physiologic data to the Flight Data System (FDS) for relay to the ground during flight. The measurements which will be taken by the RMS during the first flight will be respiration, measured at two different sites; electromyogram (EMG) at three different sites; electroencephalogram (EEG); electrocardiogram (ECG); and body temperature. These measurements taken by the RMS will assist the research team in meeting the science objectives of the RRF project.

Schonfeld, Julie E.↗
NASA NTRS1994

Ionospheric dynamics instrument investigation for the Timed Mission

The primary science objectives for the Ionospheric Dynamics Instrument (IDI) investigation are related to the global response of the ITM to energy inputs from the magnetosphere and an understanding of the ways in which electric fields are internally generated by neutral atmosphere motions in the lower thermosphere and mesosphere. At low and mid latitudes the electric fields are generated by neutral atmosphere motions and temporal resolution on time scales of a second will adequately describe the global field and allow its relationship to neutral wind motion to be established. However, the redistribution of current systems and the electrodynamics associated with plasma structures requires temporal sampling rates at the highest possible frequencies. The results of these studies are presented graphically.

Heelis, R. A.↗
NASA NTRS1994

Joint Launch + One Year Science Review of USML-1 and USMP-1 with the Microgravity Measurement Group

On September 22-24, 1993, investigators from the First United States Microgravity Laboratory (USML-1) and the First United States Microgravity Payload (USMP-1) Missions met with the Microgravity Measurement Group (MGMG) in Huntsville Alabama, to discuss science results and the microgravity environments from the respective missions. USML-1 was launched June 1992, and USMP-1 was launched October 1992. This document summarizes from the various investigations, the comprehensive results and highlights, and also serves as a combined mission report for the two missions. USML-1 was the first totally U.S.-sponsored mission dedicated to microgravity research and included 31 investigations in fluid dynamics, crystal growth, combustion, biotechnology, and technology demonstrations supported by 11 facilities. The papers in these proceedings attest to the wealth of information gleaned from the highly successful mission. On the USMP-1 mission, both the MEPHISTO and the Lambda Point experiments exceeded by over 100% their planned science objectives. The mission also marked the first time that acceleration data were down-linked and analyzed in real-time. The meeting, which concentrated on flight results, brought low-gravity investigators, accelerometer designers, and acceleration data analysis experts together. This format facilitated a tremendous amount of information exchange between these varied groups. Several of the experimenters showed results, some for the very first time, of the effects of residual accelerations on their experiment. The proceedings which are published in two volumes also contain transcriptions of the discussion periods following talks and also submittals from a simultaneous poster session.

Microgravity↗
NASA NTRS1994

Program control on the Tropical Rainfall Measuring Mission

The Tropical Rainfall Measuring Mission (TRMM), an integral part of NASA's Mission to Planet Earth, is the first satellite dedicated to measuring tropical rainfall. TRMM will contribute to an understanding of the mechanisms through which tropical rainfall influences global circulation and climate. Goddard Space Flight Center's (GSFC) Flight Projects Directorate is responsible for establishing a Project Office for the TRMM to manage, coordinate, and integrate the various organizations involved in the development and operation of this complex satellite. The TRMM observatory, the largest ever developed and built inhouse at GSFC, includes state-of-the-art hardware. It will carry five scientific instruments designed to determine the rate of rainfall and the total rainfall occurring between the north and south latitudes of 35 deg. As a secondary science objective, TRMM will also measure the Earth's radiant energy budget and lightning.

Pennington, Dorothy J.↗
NASA NTRS1995

Hitchhiker mission operations: Past, present, and future

What is mission operations? Mission operations is an iterative process aimed at achieving the greatest possible mission success with the resources available. The process involves understanding of the science objectives, investigation of which system capabilities can best meet these objectives, integration of the objectives and resources into a cohesive mission operations plan, evaluation of the plan through simulations, and implementation of the plan in real-time. In this paper, the authors present a comprehensive description of what the Hitchhiker mission operations approach is and why it is crucial to mission success. The authors describe the significance of operational considerations from the beginning and throughout the experiment ground and flight systems development. The authors also address the necessity of training and simulations. Finally, the authors cite several examples illustrating the benefits of understanding and utilizing the mission operations process.

Anderson, Kathryn↗
NASA NTRS1995

ARIM-1: The Atmospheric Refractive Index Measurements Sounding Rocket Mission

A conceptual design study of the ARIM-1 sounding rocket mission, whose goal is to study atmospheric turbulence in the tropopause region of the atmosphere, is presented. The study was conducted by an interdisciplinary team of students at the University of Alaska Fairbanks who were enrolled in a Space Systems Engineering course. The implementation of the ARIM-1 mission will be carried out by students participating in the Alaska Student Rocket Program (ASRP), with a projected launch date of August 1997. The ARIM-1 vehicle is a single stage sounding rocket with a 3:1 ogive nose cone, a payload diameter of 8 in., a motor diameter of 7.6 in., and an overall height of 17.0 ft including the four fins. Emphasis is placed on standardization of payload support systems. The thermosonde payload will measure the atmospheric turbulence by direct measurement of the temperature difference over a distance of one meter using two 3.45-micron 'hot-wire' probes. The recovery system consists of a 6 ft. diameter ribless guide surface drogue chute and a 33 ft. diameter main cross parachute designed to recover a payload of 31 pounds and slow its descent rate to 5 m/s through an altitude of 15 km. This document discusses the science objectives, mission analysis, payload mechanical configuration and structural design, recovery system, payload electronics, ground station, testing plans, and mission implementation.

Ruiz, B. Ian↗